(90) 



hemispheres which are confined to the hitter. Finally between the 

 sulcus bipartiens and the margo myelencephalicus of the cerebellnm 

 the grooves begin at the border of the hemispheres and grow out 

 mesially. The system of the grooves belonging to the Pyramis, Uvula 

 and Nodulus forms an independent system, which has no connection 

 with the systems of grooves existing in the adjacent parts of the 

 hemispheres. Consequently from a morphogenetic point of view three 

 zones may be discerned. Anterior zone: all grooves arise in the 

 middleline, grow ouf into the margin of the cerebellum or end at 

 some distance of it. In this zone the system of grooves is an unpaired one. 

 Middle zone: the grooves take their origin partly in the middleline 

 and extend to the margin of the cerebellum, partly they arise in 

 the middle of the hemispheres to which they are confined. This 

 system, of grooves is a paired one. Posterior zone : there arise grooves 

 in the middleline which are confined to a narrow band, while inde- 

 pendently of these a second system arises in the hemispheres. In 

 this zone the system of grooves j^ossesses a threefold character. The 

 cerebellum of the Primates compared to that of the other Mammals 

 is characterized by a progressive development of the anterior and 

 middle zones and a regression of the posterior zone. 



3"! . After the first stage of development having been passed there 

 arise spheres of intense surface-expansion by the side of others, where 

 this expansion is minimal. This is the case with: the most anterior 

 part of the Lobus anterior, which develops into the Lingula; further 

 Avitli the Folium veraiis, which at an early period of development 

 reaches the surface as a relatively large lamelle, and the Flocculus, 

 the surface of which enlarges very little. Spheres of intense surface- 

 expansion are: the region in the middle line, immediately surround- 

 ing the sulcus primarius; the forelip of the sulcus praepyramidalis, 

 from which arises the whole Tuber valvulae; the region between 

 the sulcus horizontalis and sulcus praepyramidalis. Especially the 

 human cerebellum is distinguished by the mighty development of 

 this part. 



The facts brought to notice in 2 and 3 lead to the conclusion 

 that the cortex of the cerebellum is not an organ with a homo- 

 geneous distributed function, but a well organised entirety with 

 localised functions. 



4^1'. In general the anterior lobe keeps ahead of the posterior 

 lobe in development, the lamellisation beginning latest in the caudal 

 part of the cerebellum. 



5^11. In connection with the difference in the mode of lamellisa- 

 tion of the zones described in 2, sulci paramediani are wanting in 



